Accelerated Biology

 Its name is derived from the Greek words  "endo” = inside or within  "crinis” = to secrete  Consists of many glands that secrete hormones into the blood stream.  In this unit, we will focus on the hypothalamus, pituitary gland, ovaries, and testes.  You will learn about other endocrine glands in later units.

 Hormones – Substances secreted by cells that act to regulate the activity of other cells in the body.  They act as chemical messengers  Functions include:  Regulate growth and development  Coordinate production, use and storage of energy  Maintain homeostasis (temperature, metabolism, etc.)  Respond to stimuli

 When you are in a “fight or flight” situation, your adrenal glands release the hormone epinephrine (formally called adrenaline). This prepares the body for stressful situations by increasing heart rate, blood pressure, blood glucose level, and blood flow to the heart and lungs.

 Negative feedback – A change in one direction stimulates a counteraction in the other direction.  High levels of a hormone, inhibit the production of more hormone  Low levels of the hormone stimulate the production of more hormone  Most hormone release is regulated through negative feedback.  Positive feedback – HIGH levels of a hormone stimulate the output of even MORE hormone

 When driving a car, you notice you are going too fast, so you take your foot of the gas pedal. OR  You notice you are going too slow, so you press down on the gas pedal.  Can you think of another analogy?

 Positve and Negative Feedback –McGraw Hill Animation Positve and Negative Feedback –McGraw Hill Animation

 Area in the brain that coordinates the activities of the nervous and endocrine systems  It monitors your internal environment (temperature, blood pressure, HORMONE LEVELS!) and responds to these conditions by sending signals to the pituitary gland in the form of hormones

 It is called the “master gland” in the body.  It receives signals from the hypothalamus and then sends signals out to many other glands in the body to secrete hormones

 Robert Wadlow had a tumor in his pituitary gland that caused an excess of growth hormone to be released. He grew to a height of 8 ft 11 inches!

 Annie Jones toured with P.T. Barnum’s circus since she was a young child.  If a women secretes excess males sex hormones, she can develop secondary male sex characteristics, such as a beard. This is a symptom of a serious medical condition, such as adrenal tumor  Most of the “bearded ladies” at freak shows were fakes